I am thinking of adding a new case to my system that will only hold 5 optical drives connected to the power supply and then, through a tray system, to a USB bus adapter and then through to my main computer. Does anyone see any flaws in this system or have any suggestions?
Much thanks
Well, I am no good at schematics and all the parts are stock. So you have to imagine a standard mid tower ATX case with 5 bays. Each bay has a 5.25 inch optical drive or a 3.5 inch drive tray with an IDE HD. All of these have adapters on the IDE connection to convert to USB 2. These USB connectors lead to a USB hub in the bottom of the case and from there out the back to one of the USB connectors on my main computer. In theory this should work. I might have to limit it to 4 drives as that is what hubs seem to come in, and I am not sure whether I need a powered hub or not.
It looks like it will cost just under $125 for all the parts, excluding the drives.
USB is not meant to handle the continuous throughput speed of modern DVD writers
USB2 with 480mbits/sec (50-60mb/sec) is not enough speed for 16x DVD writers?? Really 
Btw, I will test it in next days.
If you have other USB components plugged in it’s not enough.
USB is a shared bus. The more stuff you have plugged in, the lower your speed.
I already have my printer, mouse, and keyboard as USB, and chances are if I plugged a DVD writer in there, it won’t be able to handle 16x.
While conducting your test, try doing DVD writer plugged alone vs. DVD writer with 2 other USB components.
You’ll notice a difference.
480Mbit being the burst rate, the sustained transfer rate is very different, if you require a faster sustained rate of transfer for an external drive you should be looking into firewire
None of the 5 drives are currently being used for writing as I do all my writing on IDE connections. I will look into Firewire for any writing. One question:
If the other things are plugged into the bus but not being used or actually turned off, should that slow down the speed?
Assuming no losses and inefficiency, the absolute maximum USB2 throughput is 60Mb/s.
The maximum 16x DVD transfer rate is 22Mb/s
So theoretically, USB2 could simultaneously run:
2 drives at 16x
3 drives at 12x
5 drives at 8x
USB2-IDE interfaces tend to be supplied with a PSU for the drive, but not sure if this also powers the interface (zero USB power), or if the interface is a standard low power (100mA) or high power (500mA) device.
For anything other than high power devices (at one hub depth) an unpowered hub is ok - if you chain hubs more than one deep (hub into hub), then loading more than 5 ports at low power will exceed the limit.
Don’t bank on 100% throughput though, overheads and other devices will cut it dow… the telling factor is that even with the best possible speed, only two drives can hit the full 16x.
Even if you split them to two cables, most systems will only have a single USB2 controller endpoint, even if they have multiple USB1 channels
